Load balancer. Error "TLS Handshake Error"

Security
#1

I setuped load balancer with a few pools. One of this show Origin Health critical with error “tls handshake failure”

SSL/TLS encryption mode is Full
it was generated origin server certificates and connected to webserver through config

 listen 443 ssl so_keepalive=on; 
 ssl_certificate /etc/nginx/cloudflare.pem;
 ssl_certificate_key /etc/nginx/cloudflare.key;

How can fix that?